HELP- Weird A/C operation(semi long)

[Beer, Jerald]

A little help would be appreciated. My 94 Cabriolet went in for a
freon(r134) charge because it was not blowing real cold. Turns out that the
system needs a special adaptor to add freon in a liquid state. My regular
mechanic sent it out and it came back fine. Then it seemed to be losing some
coolness out of the side vents. According to mechanic there was a vacuum
leak that was preventing the recirc flap from closing. Didn't make sense to
me, but the car comes back, and every vent is blowing ice cold.
Unfortunately, the fan is shrieking on high speeds. I take it back and the
mech says that when the flap closed it must have sucked up a bunch of leaves
under the hood. He takes a vacuum supposedly sucks out the debris and fan is
quiet as a mouse. However, the original problem of no cold air out of the
side vents is back. I return a couple days later and the shop owner spends
half a day with the car. He checks everything and the only thing he can find
wrong is a vacuum switch at the back of the engine that appears not to be
working. He orders from Audi (3-5 business days) and sticks in a similar
Mercedes valve as a temporary measure. Well, I have medium cold  air out of
the center vents, but absolutely no air conditioned air out of the side
vents. Mechanic (20 plus years) is stumped. Can any one help out?? TIA
Regards,
Jerry
91 200qa
97 Cab
94 Cab
gsfent at prodigy.net